Cleanliness in industrial and health care settings is critical. The surfaces of equipment used for food handling, storage, or processing are major sources of microbial contamination. Such contamination can lead to decreased shelf life of products and, if pathogens are present, transmission of disease. Microbial colonies develop rapidly. Continuous monitoring of surfaces, e.g., hygiene monitoring, can help protect against the spread of disease.
Historically, microbial culturing was used to determine the presence of microorganisms. However, culturing is time consuming and, therefore, the necessary “real time” feedback to sanitation and food preparation personnel is not available. As a result, food exposed to surfaces which were later found to contain potentially harmful microorganisms could enter the food supply.
Lateral-flow chromatographic test strips have been used for a variety of diagnostic purposes. The test described herein utilizes a lateral-flow test strip to provide a means for rapid, sensitive, user-friendly, hygiene monitoring of surfaces. Material swabbed from a surface can be detected by reactions involving the pathways described herein.
Recent attention has focused on the problems of biofilms. Biofilms are created when microorganisms land on a surface and attach to its microscopic cracks and crevices. Almost immediately, the organism begins to produce a polysaccharide-like material which in hours acts as a glue to stick bacteria and viruses to the surface. Biofilms are more resistant to routine sanitizing techniques than are their free-living counterparts. It is, therefore, critical to generate rapid results, preferably within a few minutes.
Food residues on surfaces are nutrients for rapid growth of microorganisms and the potentially resultant biofilm. Such food residues are also a source of cross-contamination to other food products later exposed to the same contact surface. Therefore, proper hygiene monitoring of a surface should include detection of a broad range of contaminants, including both biofilms and residual food.
During the 1990s various rapid and efficient test methods and apparatuses were developed for the detection of contamination on surfaces. Such methods do not detect microbes directly but instead detect markers, such as ATP, which are indicative of either the presence of microbes or the existence of residual food contamination of a surface.
One such apparatus is the POCKETSWAB® (POCKETSWAB® is a registered trademark of Charm Sciences, Inc. of Lawrence, Mass.), which rapidly and efficiently detects ATP on surfaces. The POCKETSWAB® apparatus detects ATP through the reaction of luciferin and luciferase, which, in the presence of ATP, emits light. Light emission is measured using a luminometer. It is desired, and the primary object of this invention, to provide a rapid, visual test for hygiene monitoring, and thereby avoid the need for a luminometer or other reader.
There are various tests available in the field which provide a rapid and visual result, thereby reflecting the degree of surface cleanliness. Such tests are of interest for use in, for example, restaurants and supermarkets, where an instrument for reading results would not be acceptable, either because of the large volume needed or because they could not be secured, or lack ease of use.
One such test is marketed by Celsis International, PLC of Cambridge, United Kingdom, under the trademark Spotcheckä. The SPOTCHECK™ employs a cyclic “comproproportionation” reaction to detect ATP (see U.S. Pat. No. 6,043,047, issued Mar. 28, 2000, and PCT International Publication No. WO 00/36139, published Jun. 22, 2000).
One example of a method for detection of inorganic phosphate is described by N. Conrath et al, “A novel enzyme sensor for the determination of inorganic phosphate”, Analytica Chimica Acta 309 (195) 47–52 (1995), which is incorporated herein by this reference. That method, however, requires skilled laboratory personnel, is time consuming and requires equipment.
It is an object of this invention is to provide a broad-spectrum test to rapidly monitor the hygiene of a surface by detecting a variety of organic and inorganic materials, food residues and microorganisms.